linux-kernel - [patch] suspend: fix suspend on single-CPU systems

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Message-ID: <20061223155529.GA18924@elte.hu>
Date:	Sat, 23 Dec 2006 16:55:29 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Linus Torvalds <torvalds@...l.org>
Cc:	linux-kernel@...r.kernel.org, Siddha@...e.hu,
	Suresh B <suresh.b.siddha@...el.com>,
	Clark Williams <williams@...hat.com>,
	Andrew Morton <akpm@...l.org>
Subject: [patch] suspend: fix suspend on single-CPU systems

Subject: [patch] suspend: fix suspend on single-CPU systems
From: Ingo Molnar <mingo@...e.hu>

Clark Williams reported that suspend doesnt work on his laptop on 
2.6.20-rc1-rt kernels. The bug was introduced by the following cleanup 
commit:

 commit 112cecb2cc0e7341db92281ba04b26c41bb8146d
 Author: Siddha, Suresh B <suresh.b.siddha@...el.com>
 Date:   Wed Dec 6 20:34:31 2006 -0800

    [PATCH] suspend: don't change cpus_allowed for task initiating the suspend

because with this change 'error' is not initialized to 0 anymore, if 
there are no other online CPUs. (i.e. if the system is single-CPU).

the fix is the initialize it to 0. The really weird thing is that my 
version of gcc does not warn about this non-initialized variable 
situation ...

(also fix the kernel printk in the error branch, it was missing a
 newline)

Reported-by: Clark Williams <williams@...hat.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 kernel/cpu.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux/kernel/cpu.c
===================================================================
--- linux.orig/kernel/cpu.c
+++ linux/kernel/cpu.c
@@ -258,7 +258,7 @@ static cpumask_t frozen_cpus;
 
 int disable_nonboot_cpus(void)
 {
-	int cpu, first_cpu, error;
+	int cpu, first_cpu, error = 0;
 
 	mutex_lock(&cpu_add_remove_lock);
 	first_cpu = first_cpu(cpu_present_map);
@@ -294,7 +294,7 @@ int disable_nonboot_cpus(void)
 		/* Make sure the CPUs won't be enabled by someone else */
 		cpu_hotplug_disabled = 1;
 	} else {
-		printk(KERN_ERR "Non-boot CPUs are not disabled");
+		printk(KERN_ERR "Non-boot CPUs are not disabled\n");
 	}
 out:
 	mutex_unlock(&cpu_add_remove_lock);
-
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